Update rollup and rollup plugins & create rollup.config.js and use ro…

…llup CLI & generate lozad.es.js & delete build.js (ApoorvSaxena#121)

dist/lozad.es.js

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+/*! lozad.js - v1.6.0 - 2018-08-06
+* https://github.com/ApoorvSaxena/lozad.js
+* Copyright (c) 2018 Apoorv Saxena; Licensed MIT */
+
+
+/**
+ * Detect IE browser
+ * @const {boolean}
+ * @private
+ */
+const isIE = typeof document !== 'undefined' && document.documentMode;
+
+const defaultConfig = {
+  rootMargin: '0px',
+  threshold: 0,
+  load(element) {
+    if (element.nodeName.toLowerCase() === 'picture') {
+      const img = document.createElement('img');
+      if (isIE && element.getAttribute('data-iesrc')) {
+        img.src = element.getAttribute('data-iesrc');
+      }
+      if (element.getAttribute('data-alt')) {
+        img.alt = element.getAttribute('data-alt');
+      }
+      element.appendChild(img);
+    }
+    if (element.getAttribute('data-src')) {
+      element.src = element.getAttribute('data-src');
+    }
+    if (element.getAttribute('data-srcset')) {
+      element.srcset = element.getAttribute('data-srcset');
+    }
+    if (element.getAttribute('data-background-image')) {
+      element.style.backgroundImage = `url('${element.getAttribute('data-background-image')}')`;
+    }
+    if (element.getAttribute('data-toggle-class')) {
+      element.classList.toggle(element.getAttribute('data-toggle-class'));
+    }
+  },
+  loaded() {}
+};
+
+function markAsLoaded(element) {
+  element.setAttribute('data-loaded', true);
+}
+
+const isLoaded = element => element.getAttribute('data-loaded') === 'true';
+
+const onIntersection = (load, loaded) => (entries, observer) => {
+  entries.forEach(entry => {
+    if (entry.intersectionRatio > 0) {
+      observer.unobserve(entry.target);
+
+      if (!isLoaded(entry.target)) {
+        load(entry.target);
+        markAsLoaded(entry.target);
+        loaded(entry.target);
+      }
+    }
+  });
+};
+
+const getElements = selector => {
+  if (selector instanceof Element) {
+    return [selector]
+  }
+  if (selector instanceof NodeList) {
+    return selector
+  }
+  return document.querySelectorAll(selector)
+};
+
+function lozad (selector = '.lozad', options = {}) {
+  const {rootMargin, threshold, load, loaded} = {...defaultConfig, ...options};
+  let observer;
+
+  if (window.IntersectionObserver) {
+    observer = new IntersectionObserver(onIntersection(load, loaded), {
+      rootMargin,
+      threshold
+    });
+  }
+
+  return {
+    observe() {
+      const elements = getElements(selector);
+
+      for (let i = 0; i < elements.length; i++) {
+        if (isLoaded(elements[i])) {
+          continue
+        }
+        if (observer) {
+          observer.observe(elements[i]);
+          continue
+        }
+        load(elements[i]);
+        markAsLoaded(elements[i]);
+        loaded(elements[i]);
+      }
+    },
+    triggerLoad(element) {
+      if (isLoaded(element)) {
+        return
+      }
+
+      load(element);
+      markAsLoaded(element);
+      loaded(element);
+    }
+  }
+}
+
+export default lozad;